1. α
    Alpha, risk of rejecting the null hypothesis erroneously
  2. AFR
    Average failure rate
  3. ANOM
    Analysis of means
  4. ANOVA
    Analysis of variance
  5. AQL
    Acceptable quality level
  6. ARL
    Average run length
  7. β
    Beta, risk of not rejecting the null hypothesis erroneously
  8. c chart
    Control chart for nonconformities
  9. C&E
    Cause and effect (diagram)
  10. CL
    Center line in an SPC chart
  11. CDF
    Cumulative distribution function
  12. Cp
    Capability index which shows the process capability potential but does not consider how centered the process is.
  13. Cpk
    Capability index used to compare the natural tolerance of a process within the specification limits. Cpk has a value equal to Cp if the process is centered on the nominal; if Cpk is negative, the process mean is outside of the specification limits; if Cpk is between 0 and 1 then the natural tolerances of the process falls outside the spec limits.
  14. COPQ
    Cost of poor quality
  15. CTC
    Critical to cost
  16. CTD
    Critical to delivery
  17. CTP
    Critical to process
  18. CTQ
    Critical to quality
  19. CUSUM
    Control chart which plots the cumulative deviation of each subgroup’s average from the nominal value.
  20. D chart
    Demerit chart
  21. DF
    Degrees of freedom
  22. DOE
    Design of experiments
  23. DPM
    Defects per million
  24. DPMO
    Defects per million opportunities
  25. FMEA
    Failure mode and effects analysis
  26. Gage R&R
    Gage repeatability and reproducibility
  27. Ho
    Null hypothesis
  28. Ha
    Alternative hypothesis
  29. KCA
    Knowledge centered activity
  30. KPIV
    Key process input variables
  31. KPOV
    Key process output variables
  32. LCL
    Lower control limit (in SPC)
  33. µ
    Mu, population true mean
  34. μ
    Estimate of population mean
  35. MS
    Mean square
  36. MSA
    Measurement Systems Analysis
  37. MTBF
    Mean time between failures
  38. n
    Sample size
  39. np (chart)
    SPC chart of number of nonconforming items
  40. NGT
    Nominal group technique
  41. P
  42. p (chart)
    Control chart of the proportion of defective units (or fraction defective) in a subgroup. Based on the binomial distribution
  43. P Value
    The probability of making a Type I error.
  44. PDF
    Probability density function
  45. ppm
    Parts per million (defect rate)
  46. Pp
    Performance index (AIAG l995b) (calculated using "long-term" standard deviation)
  47. Ppk
    Performance index (AIAG 1995b) (calculated using "long-term" standard deviation)
  48. P/T
    Precision to tolerance ratio
  49. QFD
    Quality function deployment
  50. R
    Range (in SPC)
  51. RSM
    Response surface methodology
  52. RTY
    Rolled Throughput Yield
  53. r
    Number of failures, correlation coefficient
  54. R2
    Coefficient of determination
  55. s
    Sigma, population standard deviation
  56. Estimate for population standard deviation
  57. s
    Standard deviation of a sample
  58. S Chart
    Sample standard deviation chart
  59. SPC
    Statistical process control
  60. SS
    Sum of squares
  61. UCL
    Upper control limit (SPC)
  62. u (chart)
    SPC chart of number of nonconformities per unit
  63. Mean of a variable x
  64. Median of variable x
  65. chart
    SPC chart of means (i.e., x-bar chart)
  66. Xmr (chart)
    SPC chart of individual and moving range measurements
Card Set
Six Sigma Symbols